Method for incorporating nitrogen containing methine light absorbers in pet and compositions thereof

Abstract

The present invention is a method for efficiently incorporating a nitrogen containing methine light absorber into a polyester resin. The method includes forming a reaction mixture comprising combining a diol component, a diacid component selected from the group consisting of dicarboxylic acids, dicarboxylic acid derivatives, and mixtures thereof, an antimony containing compound, a phosphorus containing compound, a metal containing compound, and a nitrogen containing methine light absorber. The reaction mixture is polymerized in a polycondensation reaction system. In another embodiment the light absorber is added while the reaction products of one reactor are being transferred to the next reactor in the polycondensation reaction system. The present invention is also directed articles made from the polyester resin.

Description

BACKGROUND OF THE INVENTION [0001] 1. Field of the Invention [0002] The present invention relates to a method for efficiently incorporating light absorbing compounds into a polyester composition. More particularly, the present method relates to incorporating a nitrogen containing methine light absorbing compound into a polyester composition. [0003] 2. Background Art [0004] Polyester is a polymeric resin widely used in a number of packaging and fiber based applications. Poly(ethylene terephthalate) (“PET”) or a modified PET is the polymer of choice for making beverage and food containers such as plastic bottles and jars used for carbonated beverages, water, juices, foods, detergents, cosmetics, and other products. [0005] In the typical polyester forming polycondensation reaction, a diol such as ethylene glycol is reacted with a dicarboxylic acid or a dicarboxylic acid ester. The reaction is accelerated by the addition of a suitable reaction catalyst. Since the product of the polyeste...

AI Technical Summary

Benefits of technology

[0009] In one embodiment, a method comprises forming a reaction mixture substantially free of a titanium containing ester exchange catalyst compound and comprising combining a diol, a diacid component selected from the group consisting of dicarboxylic acids, dicarboxylic acid derivatives, and mixtures thereof, an antimony containing compound in an amount of less than 0.1% of the total weight of the reaction mixture, a phosphorus containing compound present in an amount of less than about 0.1% of the total weight of the reaction mixture, a metal containing compound selected from the group consisting of zinc containing compounds and / or manganese containing compounds, present in an amount from about 10 ppm to about 300 ppm, and a light absorber with polyester reactive moieties. The antimony containing compound, the phosphorus containing compound, and the metal-containing compound comprise the catalyst system used to promote the condensation polymerization that occurs in the method of the invention. The reaction mixture is then polymerized in a polycondensation reaction system in the absence of the titanium ester exchange catalyst compound. The polycondensation reaction system is characterized by having a first reaction chamber, a last reaction chamber, and optionally one or more intermediate reaction chambers between the first reaction chamber and the last reaction chamber. The reaction system is operated in series such that the reaction mixture is progressively polymerized in the first reaction chamber, the one or more intermediate reactions, and the last reaction chamber. Accordingly, as the reaction mixture proceeds through the series of reaction chambers, polymerization occurs and a polyester is formed by the condensation reaction of the diol and the diacid component. Moreover, volatile compounds are removed in each reaction chamber and the average molecular weight of the polyester increases from reactor to reactor by the decreasing reaction pressures of the successive reaction chambers.

Problems solved by technology

It has been observed, however, that some light absorbing compounds are somewhat volatile causing the yield of these light absorbers in the formed polyester to be somewhat less than 100% (values of 80% to 85% are typical).

Moreover, these compounds may plug the equipment by condensing in the process lines.

The loss of light absorber results in added costs for the polyester formation because of the down time needed to clean process lines and because of the relatively high cost of these compounds.

Images